My office looks out over my garden and I routinely watch as deer jump the four foot fence to feast on my roses. I have used Liquid Fence which helps a bit. I have used Gain drier sheets which help a bit, too. But neither has been as effective as I'd wish. One is smelly; the other unsightly. Both require regular attention if they are to be effective.
Last July I started an experiment. My garden is molested by deer and gophers alike. I wanted to see if their palates could detect poisonous plants. And if poisonous plants could slow them down. I planted: datura, castor bean (ricinis Carmencita), foxgloves (digitalis) and larkspur (delphinium ajacis.) In locations where datura thrived, I found a slight decrease in gopher activity, and I think the experiment is worth doing again, although the plant does send out huge roots all through the garden.
The turning point came in late fall when the only green plant in my garden was a large patch of larkspur. I went out one morning and saw they were all nibbled to about two inches in height. It could only have been deer; the gophers pull the individual plants down into their burrows. I have noticed that since this moment the deer have sometimes stopped to look into the garden as they pass. But they have pretty much stopped jumping over the fence.
I keep intending to spray everything with Bobbex and forgetting to actually do so. I've seen deer pass my garden fence two or three times this week, which suggests they have probably passe four or six times. I've seen no evidence of rose damage.
I doubt that larkspur are a perfect solution; but they do get some efficacy from the fact that deer have very good memories. Right now there are several places where larkspur nearly envelop a hybrid tea rose. It looks a little odd. But the rose so enveloped looks very happy beneath this temporary shroud of protection.
I cannot explain it, but the damage that comes from squirrels seems lower this year, too. It's almost as if they like to nibble on larkspur, too.
This spring, outside the fenced area that houses my rose garden, I did put in a raised bed with a wire mesh floor and a dual fence around it to give more complete protection from gophers, deer, desert rats, rabbits, squrrels, chipmunks and javelina. It's in its first year, so we will see if the corn, zucchini, beans, and tomatoes grown there will survive. We'll see if next year we will be planting some more esoteric veggetables such as bitter melon. Regardless of what I plant there it would take about five hundred years of great harvests for it to pay for itself. But there is something reassuring to having it there nonetheless.